In cooperation with the U.S. Air Force, Aeronautical Systems Center, Environmental Management Directorate, Wright-Patterson Air Force Base, Ohio

Analyses and Estimates of Hydraulic Conductivity From Slug Tests in Alluvial Aquifer Underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas

To hoist Data logger N Naval Air Station-Joint A Reserve Base A' Static water Air Force Carswell Field level Plant 4 (NAS–JRB) (AFP4) Slug Pressure transducer A A' 700 Meandering AFP4 NAS–JRB Road Creek Goodland Limestone 650

Goodland Limestone West Fork Fill material and alluvial deposits Walnut Formation Trinity 600 River ABOVE NAVD 88 NAVD ABOVE ALTITUDE, IN FEET ALTITUDE, 550 Paluxy Formation

500 0 2,0004,000 6,000 8,000 10,000 DISTANCE, IN FEET

Scientific Investigations Report 2004–5225

U.S. Department of the Interior U.S. Geological Survey Blank Page Analyses and Estimates of Hydraulic Conductivity From Slug Tests in Alluvial Aquifer Underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas

By Natalie A. Houston and Christopher L. Braun

In cooperation with the U.S. Air Force, Aeronautical Systems Center, Environmental Management Directorate, Wright-Patterson Air Force Base, Ohio

Scientific Investigations Report 2004–5225

U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior Gale A. Norton, Secretary

U.S. Geological Survey Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2004 For sale by U.S. Geological Survey, Information Services Box 25286, Denver Federal Center Denver, CO 80225

For more information about the USGS and its products: Telephone: 1-888-ASK-USGS World Wide Web: http://www.usgs.gov/ Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report.

Houston, N.A., and Braun, C.L., 2004, Analyses and estimates of hydraulic conductivity from slug tests in alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas: U.S. Geological Survey Scientific Investigations Report 2004–5225, 22 p. iii

Contents

Abstract ...... 1 Introduction ...... 1 Study Area ...... 3 Previous Studies and Available Data ...... 4 Slug Tests ...... 9 Theory ...... 9 Equipment ...... 9 Data Collection ...... 10 Analyses and Estimates of Hydraulic Conductivity ...... 12 Summary ...... 21 References ...... 21

Plate

[Plate is in pocket] 1. Map showing locations of study area and wells in which slug tests were completed to estimate hydraulic conductivity in alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas

Figures

1. Map showing location of study area and distribution of trichloroethene (TCE) plume in alluvial aquifer underlying Air Force Plant 4 (AFP4) and Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB), Fort Worth, Texas, August 2003 ...... 2 2. Generalized west-to-east hydrogeologic section through study area, Air Force Plant 4 (AFP4) and Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB), Fort Worth, Texas ...... 3 3–5. Graphs showing: 3. Slug-induced water-level change (normalized) relative to time from slug-test data collected at Air Force Plant 4 (AFP4) and Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB), Fort Worth, Texas, October 2002 ...... 13 4. Slug-induced water-level change (normalized) relative to time from slug-test data collected at Air Force Plant 4 (AFP4) and Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB), Fort Worth, Texas, August 2003 ...... 17 5. Frequency distribution of hydraulic-conductivity values obtained from analyses of slug-test data collected from wells in alluvial aquifer, Air Force Plant 4 (AFP4) and Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB), Fort Worth, Texas ...... 20

Tables

1. Geologic and hydrologic characteristics of hydrogeologic units underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas ...... 4 iv

2. Locations and results of pre-2002 aquifer and slug tests used to estimate hydraulic conductivity in alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas ...... 5 3. Diameters of wells and dimensions of slugs used to estimate hydraulic conductivity in alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas ...... 10 4. Location and site-characteristic data for wells used to estimate hydraulic conductivity in alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas ...... 11 5. Summary of hydraulic-conductivity estimates, slug discrepancies, and 90-percent recovery times for wells in alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas ...... 12

Datum

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88). Analyses and Estimates of Hydraulic Conductivity From Slug Tests in Alluvial Aquifer Underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas

By Natalie A. Houston and Christopher L. Braun

Abstract (NAS–JRB) (fig. 1), adjacent to AFP4, opened as Tarrant Field Airdrome in June 1942, when it was used for flight training and aircraft operations. It now serves as a base and training facility This report describes the collection, analyses, and distribu- for the U.S. Navy and Marines and reserve forces of the U.S. tion of hydraulic-conductivity data obtained from slug tests Air Force and Army. completed in the alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Manufacturing at AFP4 required various solvents, paints, Worth, Texas, during October 2002 and August 2003 and sum- metals, oils, fuels, and other toxic chemicals; the associated marizes previously available hydraulic-conductivity data. The wastes—trichloroethene (TCE) among them—were dumped U.S. Geological Survey, in cooperation with the U.S. Air Force, into on-site landfills during most of the plant’s history (Envi- completed 30 slug tests in October 2002 and August 2003 to ronmental Science and Engineering, Inc., 1994). Ground water obtain estimates of horizontal hydraulic conductivity to use as containing TCE is known to have leaked downward from the initial values in a ground-water-flow model for the site. The alluvial aquifer into the Paluxy aquifer in at least two areas tests were done by placing a polyvinyl-chloride slug of known (Kuniansky and Hamrick, 1998, p. 2). TCE has entered the volume beneath the water level in selected wells, removing the uppermost (“upper sand”) interval of the Paluxy aquifer slug, and measuring the resulting water-level recovery over beneath parts of the east parking lot of AFP4 and flight line of time. The water levels were measured with a pressure trans- NAS–JRB (pl. 1); and lesser amounts of TCE have reached ducer and recorded with a data logger. Hydraulic-conductivity parts of the upper and middle zones of the Paluxy aquifer on the values were estimated from an analytical relation between the west side of AFP4 between landfill 3 (west of Bomber Road) instantaneous displacement of water in a well bore and the and former landfill 1 (now covered by the west parking lot). resulting rate of head change. Although nearly two-thirds of the The U.S. Geological Survey (USGS), in cooperation with tested wells recovered 90 percent of their slug-induced head the U.S. Air Force, is studying the hydrogeology beneath AFP4 change in less than 2 minutes, 90-percent recovery times ranged and NAS–JRB to better understand the ground-water-flow from 3 seconds to 35 minutes. The estimates of hydraulic con- system, particularly as it relates to the subsurface movement of ductivity range from 0.2 to 200 feet per day. Eighty-three contaminants, including TCE. As a precursor to constructing a percent of the estimates are between 1 and 100 feet per day. ground-water-flow model for the site, the USGS did a series of slug tests to obtain initial estimates of horizontal hydraulic con- ductivity for use in the model. This report describes the collec- Introduction tion, analyses, and distribution of hydraulic-conductivity data obtained from slug tests completed at AFP4 and NAS–JRB Air Force Plant 4 (AFP4) in Fort Worth, Tex. (fig. 1), during October 2002 and August 2003. Of 30 completed tests, was completed in 1942 and used to build military aircraft three were done on wells at AFP4 and 27 were done on wells at during World War II. Subsequently, this government-owned, NAS–JRB. The report also summarizes graphically and in tab- contractor-operated facility was used to manufacture radar ular form the results of available aquifer and slug tests done at units, missile components, and spare parts, in addition to air- AFP4 and NAS–JRB, primarily by consultants to the U.S. Air craft. Naval Air Station-Joint Reserve Base Carswell Field Force, before 2002. 2 Analyses and Estimates of Hydraulic Conductivity in Alluvial Aquifer Underlying AFP4 and NAS–JRB, Fort Worth, Texas Fort Worth TEXAS Study area TCE concentrations, per liter in micrograms Less than 5.0 5.0 to 49.9 50.0 to 499.9 500.0 to 4,999.9 5,000.0 to 10,000 area boundary Study AFP4 and NAS–JRB boundary EXPLANATION

River and Naval Air Station-Joint Reserve Base 0.5 MILE Trinity

Fork t

Wes 0.25 Creek 0

h

Branc

Far mers LAKE WORTH (NAS–JRB) Carswell Field Naval Air Station- Joint Reserve Base (AFP4) 97º26' 97º25' 97º24'

Air Force Plant 4

Creek

Road g White Settlement

Building 181 Meanderin Location of study area and distribution of trichloroethene (TCE) plume in alluvial aquifer underlying Air Force Plant 4 (AFP4) 4 (AFP4) Plant Force Air underlying aquifer alluvial in plume (TCE) trichloroethene of distribution and area study of Location Base from U.S. Air Force, Aeronautical Systems Center 32º47' 32º46' Carswell FieldCarswell (NAS–JRB),Worth, Fort Texas, August 2003. Figure 1. Introduction 3

N

Naval Air Station-Joint A Reserve Base A' Air Force Carswell Field Plant 4 (NAS–JRB) (AFP4)

A A' 700 Meandering AFP4 NAS–JRB Road Creek Goodland Limestone 650 Goodland Li mestone West Fork Fill mater Walnut Formation ial and alluvial deposits Trinity 600 River

ABOVE NAVD 88 NAVD ABOVE Paluxy Formation ALTITUDE, IN FEET ALTITUDE, 550

500 0 2,0004,000 6,000 8,000 10,000 DISTANCE, IN FEET

Figure 2. Generalized west-to-east hydrogeologic section through study area, Air Force Plant 4 (AFP4) and Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB), Fort Worth, Texas.

Study Area Three formations of Cretaceous age crop out in the study area: the Paluxy and Walnut Formations and the The study area is in northwest Fort Worth, Tex. The area Goodland Limestone (fig. 2; table 1). Terrace alluvial deposits is drained primarily by the West Fork Trinity River (pl. 1; of Pleistocene age, recent alluvial deposits of Holocene age, fig. 1). Farmers Branch and Meandering Road Creeks are small, and localized fill material overlie these formations and intermittent tributaries to the West Fork Trinity River that collectively form the alluvial aquifer in the area. The alluvial locally drain AFP4 and NAS–JRB. deposits are composed of poorly sorted, locally cross-bedded, The study area includes AFP4 and NAS–JRB south of the mostly unconsolidated gravel, sand, silt, and clay. The Good- southwestern shoreline of Lake Worth. AFP4 is bounded on the east by NAS–JRB and on the west roughly by Meandering Road land Limestone and Walnut Formation together form the Creek (pl. 1) and Bomber Road. NAS–JRB is bounded on the Goodland-Walnut confining unit. The Paluxy Formation consti- east roughly by State Highway 183 (toward the south) and West tutes the Paluxy aquifer. The alluvial and Paluxy aquifers are Fork Trinity River (toward the north). The community of White hydraulically connected where the intervening confining unit is Settlement is southwest of both facilities. thin or absent. 4 Analyses and Estimates of Hydraulic Conductivity in Alluvial Aquifer Underlying AFP4 and NAS–JRB, Fort Worth, Texas

Table 1. Geologic and hydrologic characteristics of hydrogeologic units underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas (modified from Kuniansky and others, 1996, table 4).

[mya, million years ago; AFP4, Air Force Plant 4]

Thickness of Permeability or Stratigraphic Hydrogeologic hydrogeologic Lithologic Era System Series/group water-yielding unit unit unit characteristics characteristics (feet)

Quaternary Holocene Fill material Alluvial 0–65 Construction debris Permeability varies, (1.8 mya aquifer gravels and sands to Recent alluvial Gravel, sand, silt, and permeable Cenozoic present) deposits clay Pleistocene Terrace Gravel, sand, silt, and Permeability varies, alluvial clay gravels and sands deposits permeable

Cretaceous Comanchean/ Goodland Goodland- 0–90 Massive white, fossilif- Very low permeability (65 to Fredericksburg Limestone Walnut erous limestone, inter- where not weathered— 140 mya) confining bedded with marl and considered confining unit shale unit

Walnut Medium to dark gray Very low permeability— Formation clay and limestone considered confining with shell conglom- unit erates, fossiliferous, Mesozoic Gryphaea beds Comanchean/ Paluxy Paluxy aquifer 130–175 Light gray to greenish- Considered aquifer, Trinity Formation gray fine- to coarse- yields small to mod- grained sandstone and erate quantities of dense mudstone water

Glen Rose Basal 150, range Brownish-yellow and Low permeability— Formation confining unknown at gray alternating lime- considered confining unit AFP4 stone, marl, shale, and unit in area of AFP4 sand

Previous Studies and Available Data Many aquifer and slug tests were completed during the 1980s in wells constructed by Hargis and Montgomery, Inc. Before 2002, more than 160 aquifer (pumping/recovery) (1983). Referring to the alluvial deposits as the “upper zone,” tests and slug tests are known to have been conducted at AFP4 these investigators described it as a shallow unit including con- and NAS–JRB; the locations, methods, and results of most of struction fill and alluvium above the Goodland Limestone and these tests are listed in table 2. The locations of wells providing Walnut Formation to a depth of about 40 feet. Subsequent work, pre-2002 hydraulic-conductivity data are shown on plate 1. however, has shown that many of the Hargis and Montgomery, Table 2 and plate 1 provide information for only those wells Inc. (1983) wells are screened in the uppermost, weathered sec- with known spatial coordinate data. Most previous authors tion of the Goodland-Walnut confining unit and thus do not rep- reported hydraulic-conductivity values to one to three signifi- resent solely the alluvial aquifer. Consequently, no data from cant figures. For consistency in this report, all hydraulic con- any Hargis and Montgomery, Inc. (1983) wells known to be ductivities are reported to one significant figure. mostly or completely screened in Goodland Limestone were The USGS completed 11 alluvial aquifer slug tests during used for this report. August 1996 (E.L. Kuniansky, U.S. Geological Survey, written During 1986, Intellus Corporation (1986) completed commun., 1997) as part of an ongoing phytoremediation project 23 slug tests in wells penetrating areas of potential contamina- (Shah and Braun, 2004). Consulting firms completed the tion, or “areas of concern” near AFP4. These wells were com- remainder of all previous aquifer and slug tests; those most pleted within old landfills, die yards, chemical pits, chrome pits, relevant to the current (2001) study are chronicled below. and other areas designated as areas of concern. Despite being Introduction 5 ) ) ) ) commun., 1997) commun., 1997) commun., 1997) commun.,1997) commun.,1997) commun.,1997) commun.,1997) commun.,1997) commun.,1997) commun.,1997) n commun.,1997) Source of test data Air Force Plant 4 and Naval Air Station- Air Naval and 4 Plant Force Air AirForce Plant 4 and Naval Air Station- DDMMSS.SS); CPB, Cooper-Bredehoeft-Papadopulos method for analyzing method, or both Test method or analysis Test date Hydraulic conductivity Latitude Longitude 2 Easting 1 Northing Locationsresultspre-2002 andused of estimate aquifertests hydraulic alluvial to slug conductivity and aquifer in underlying Locations and results of pre-2002 aquifer and slug tests used to estimate hydraulic conductivity in alluvial aquifer underlying aquifer in alluvial conductivity hydraulic estimate to used tests slug and aquifer pre-2002 of and results Locations Well number GMI–22–02MGMI–22–03M 6966632.930 2296187.360GMI–22–04M 6966219.920 324630.79 972601.65 2298539.370GMI–22–05M 6967250.520 324626.46 2297340.450 972534.15GMI–22–06M 6966940.330 324636.78 10 972548.07 2299432.080GMI–22–07M 6967004.480 324633.50 40 972523.61 2298186.580USGS04T 6969018.680 324634.26 30 972538.19 2298322.510WCHMHTA001 324654.18 1998 6966632.500 50 972536.35WCHMHTA002 2293702.380 1998 Slug (Bouwer test 6968758.980 Rice) & 6967545.100 324631.03 50WCHMHTA003 2299177.670 2294818.470 972630.75 1998 Slug (Bouwer test Rice) 324651.52 & 6967958.330 324639.95 60WCHMHTA004 972526.37 972617.57 2295039.040 1998 Slug (Bouwer test Rice) & 6967949.300 324644.02WCHMHTA005 972614.94 2295041.060 1998 7 Slug (Bouwer test Rice) & 6967495.680 324643.93 80WCHMHTA006 972614.92 2295662.840 1998 9 Slug (Bouwer test Rice) & 6967494.620 324639.37WCHMHTA007 50 972607.69 2295671.900 Slug CH2M (Bouwer test Hill, Inc. Rice) & (2000) 6967910.330 324639.36WCHMHTA009 1998 972607.58 2295910.420 5 CH2M Hill, Inc.(2000) 1998 6968444.690 324643.46WCHMHTA010 1998 972604.74 2296663.990 Slug (Bouwer test Rice) & 6 CH2M Hill, Inc.(2000) 6968440.060 324648.66 1998 Slug (Bouwer test Rice) & WCHMHTA011 20 2296660.060 972555.85 Slug (Bouwer test Rice) & CH2M Hill, Inc.(2000) 6969295.200 324648.62 Slug (Bouwer test Rice) & WCHMHTA012 1998 50 972555.90 2297328.380 CH2M Hill, Inc.(2000) 6968645.440 324657.01WITCTA010 1998 10 972547.96 2297691.140 Slug (Bouwer test Rice) & CH2M Hill, Inc.(2000) 324650.55 1998WITCTA024 40 972543.79 Slug (Bouwer test Rice) & 6967694.530 200 1998 Slug (Bouwer test Rice) & RW–1U 2298753.180 CH2M Hill, Inc.(2000) 6965971.780 324641.03 1998 CH2M Hill, Inc.(2000) Slug (Bouwer test Rice) & W–151 40 972531.47 2298956.020 CH2M Hill, Inc.(2000) 324623.97 1998 CH2M Slug Hill, (Bouwer test Inc.(2000) Rice) & WINTTA048 972529.30 1998 200 Slug (Bouwer test Rice) & WINTTA049 6965267.600 CH2M Hill, Inc.(2000) Slug (Bouwer test Rice) & 6965253.000 2292468.700 1998WJEGTA513 20 2292512.000 324617.65 CH2M Hill, Inc.(2000) 6964980.930 6965301.000 324617.50 972645.36 CH2M Slug (Bouwer test Hill, Inc. Rice)(2000) & 2292475.310WJEGTA514 2292458.000 972644.86 1998 324614.81 6962977.500 324617.98 CH2M Hill, Inc.(2000) 972645.32WJEGTA515 2296754.000 972645.48 Slug (Bouwer test Rice) & 30 6962864.000 324554.56 1998 CH2M Hill, Inc.(2000) 20WJEGTA516 972555.44 2296751.000 6962863.000 324553.44 CH2M Hill, 40 Inc.(2000) Slug (Bouwer test Rice) & 30WJEGTA518 972555.49 2296894.000 CH2M Hill, Inc.(2000) 6962969.000 324553.41 30WJEGTA520 2296860.000 972553.82 1997 6962950.000 324554.46 1997 CH2M Hill, Inc.(2000) 20WJEGTA523 972554.20 2296714.000 HantushLeaky 1997 6962879.000 324554.29 1997 HantushLeaky WJEGTA525 972555.92 2296810.000 3 CH2M Hill, Inc.(2000) 6962887.000 324553.58 1996 HantushLeaky HantushLeaky 30WJEGTA527 972554.80 2296845.000 6962800.000 324553.65 1996 Slug (Bouwer test Rice) & CH2M Hill, Inc.(2000) 30WJEGTA528 972554.39 2296820.000 6962856.000 324552.80 Slug (Bouwer test Rice) & 20 1996WJEGTA529 972554.69 2296937.000 6962815.000 324553.34 1996 50FT09–12A 2296880.000 972553.32 Slug (Bouwer test Rice) & 6962759.000 324552.94 1996 Slug (Bouwer test Rice) & FT09–12B 972553.99 2296997.000 7 324552.37 1996 Slug (Bouwer test Rice) & 10FT09–12C 972552.62 6960549.800 1996 E.L. Slug (Bouwer test Kuniansky, Rice) & U.S. Geological Survey(written 2295439.200LF04–4A 9 324530.67 6960709.300 100 DukeEngineering E.L. Slug (Bouwer and test Kuniansky, Services, Rice) & U.S. Inc. Geological (1998) Survey(written 972611.13 2295697.400 1996LF04–4D DukeEngineering and Services, Inc. (1998) 6960590.300 324532.22 1996 972608.09 2295771.500 DukeEngineering and Services, Inc. (1998) E.L. Slug (Bouwer test Kuniansky, Rice) & U.S. Geological Duke SurveyEngineering(written and Services, Inc. (1998) 324531.04 6960300.480 E.L. Slug Kuniansky, (Bouwer test Rice) U.S. & Geological Survey(written 972607.23 1996 2 1996 2295852.980 6960828.000 324528.16 E.L. Kuniansky, U.S. Geological Survey(written Slug (Bouwer test Rice) & 4 2296412.390 972606.31 Slug (Bouwer test Rice) & 324533.32 E.L. Kuniansky, U.S. Geological Survey(written 8 972559.70 E.L. Kuniansky, 1991 U.S. Geological Survey(written 1 1991 Slug (Bouwer test Rice) & E.L. Kuniansky, 20 U.S. Geological Survey(written E.L. Kuniansky, U.S. Geological Survey 1991(written Slug (Bouwer test Rice) & Slug (Bouwer test Rice) & E.L. Kuniansky, U.S. Geological 1991 Survey(written E.L. Kuniansky, U.S. Geological Survey(writte 1991 Slug (Bouwer test Rice) & Slug (Bouwer test Rice) & Environmental Science and Engineering, Inc.(1994 Environmental Science and Engineering, Inc.(1994 Environmental Science and Engineering, Inc.(1994 Environmental Science and Engineering, Inc.(1994) Env Joint Reserve Base Carswell Field, Fort Worth, Texas—Continued. Worth, Fort Field, Carswell Base Reserve Joint Table 2. Table JointBaseCarswell Reserve Fort Field, Worth, Texas. Table 2. [Hydraulic conductivityin feet per day reported one to significant figure; latitude and longitudein degrees/minutes/seconds ( confined-aquifer slug-test data;unknown] --, 6 Analyses and Estimates of Hydraulic Conductivity in Alluvial Aquifer Underlying AFP4 and NAS–JRB, Fort Worth, Texas ) ) 4) Source of test data Air Force Plant 4 and Naval Air Station- Air Naval and 4 Plant Force Air method, or both Test method or analysis Test date Hydraulic conductivity Latitude Longitude 2 Easting 1 Northing Locationsresultspre-2002 andused of estimate aquifertests hydraulic alluvial to slug conductivity and aquifer in underlying Well number LF04–4ELF04–4GLF05–5C 6961036.040LF05–5E 2296407.000 6961224.130 324535.38LF01–1D 2296658.930 972559.74 324537.22 6961720.050LF01–1F 972556.77 2295993.730 324542.19 6961177.000LF04–02 20 972604.50 2295546.000 6964288.180 324536.86LF04–02 10 2301412.720 972609.81 324607.05 6964438.040LF04–03 972500.73 2301376.050 5 324608.54 1991 6961113.060CAR–RW1 972501.14 2296309.100 6 1991 6961113.060 324536.15 Slug (Bouwer test Rice) & CAR–RW2 2296309.100 972600.88 .03 6961063.960 324536.15 Slug (Bouwer test Rice) & CAR–RW10 6960869.000 1991 972600.88 2296305.770 4 2296755.000 324535.67 800CAR–RW10 6961223.000 324533.70 1991 Slug (Bouwer test Rice) & 972600.92 1991 2296673.000 972555.68 6961279.060 700CAR–RW10 324537.21 2296078.880 Slug (Bouwer test Rice) & 972556.60 Slug (Bouwer test Rice) & 6961279.060 324537.82 800WHGLTA046 300 1991 2296078.880 972603.55 1990 6961279.060 324537.82 EnvironmentalWHGLTA047 Science and Engineering, Inc.(1994 200 2296078.880 6961298.486 972603.55 Slug (Bouwer test Rice) & 1990 Aquifer test (drawdown) 324537.82 2296089.683 100 Environmental Science and Engineering, Inc.(1994WHGLTA047 972603.55 6961250.473 324538.01 1990 Aquifer test (recovery) 972603.42 2296102.197 100 1993WHGLTA047 6961250.473 Environmental 324537.54 Science and Engineering, Inc.(1994) Multiple-well aquifer test (recovery) 2296102.197 972603.28 100 1993 Single-wellWP07–10B aquifer test 6961250.473 324537.54 100 Environmental Science and Engineering, Inc.(1994) 2000 Environmental Science and Engineering, 2296102.197 972603.28 Inc.(199 Single-wellWP07–10B aquifer test(Neuman) 324537.54 200 2000 Multiple-well aquifer test (Cooper-Jacob) 972603.28 HydroGeoLogic, Inc. (2002) WP07–10B 6961277.460 HydroGeoLogic, Inc. 200 (2002) Environmental Science and Engineering, 2000 Inc.(1994) Multiple-well 2296040.450 aquifer test (Neuman) 2000FT08–11A 6961277.460 324537.81 HydroGeoLogic,Inc. 200 (2002) Multiple-well 2296040.450 972604.00aquifer test (Theis) HydroGeoLogic,Inc. (2002) 2000HM–123 Multiple-well 6961277.460 324537.81 aquifer test (Theis) 2296040.450 972604.00 HydroGeoLogic,Inc. (2002) HydroGeoLogic, Inc. (2002) ITMW–01T 2000 Multiple-well 324537.81 aquifer 100 test (Cooper) 6962320.500 972604.00 2295877.800 HydroGeoLogic, 2000LF05–5EInc. (2002) Multiple-well aquifer 100 test (Neuman) 324548.15 HydroGeoLogic, Inc. (2002) 972605.78 6961638.500 6961062.050WHGLRW016 Multiple-well aquifer 100 test (Theis) HydroGeoLogic, Inc. (2002) 2295272.600 2298967.140 HydroGeoLogic, Inc. (2002) 2000 324541.46 324535.38WHGLRW017 6961034.950 HydroGeoLogic, 972612.95 Inc. 972529.75 (2002) 2299201.470 20 6961177.140 2000 Multiple-wellWHGLRW019 aquifer test (Cooper) 6960727.110 324535.09 2295546.400 972527.01 2299000.590 324536.86 2000 200 Multiple-wellWHGLTA002 300 aquifer test (Neuman) 6960684.230 324532.06 HydroGeoLogic, Inc. 972609.80 (2002) 972529.40 2298620.190 Multiple-wellWHGLTA048 aquifer test (Theis) 324531.68 100 6962377.910 2001 HydroGeoLogic, 972533.86 Inc. (2002) 2296111.390WHGLTA056 300 50 HydroGeoLogic, 6960916.200 324548.69 Inc. (2002) Slug (Bouwer test Rice) & 2001 2001 2298714.830 972603.04WHGLTA701 100 6960787.360 324533.96 Slug (Bouwer test Rice) & 2001 972532.73 2295827.620 Slug (Bouwer test Rice) & WHGLTA705 HydroGeoLogic, Inc. (2002) 6961835.730 324532.98 10 2001 972606.56 2295332.860 2001 Slug (Bouwer test Rice) & WHGLTA706 6962002.920 324543.40 10 2001 972612.22 2296026.740 Slug (Bouwer test Rice) & Slug (Bouwer test Rice) & WITCTA057 6962146.170 324544.99 50 972604.08 2296030.820 Slug (Bouwer test Rice) & WP07–10A 324546.40 2001 HydroGeoLogic,Inc. (2002) 6961308.486 40 972604.01WP07–10C 2295952.354 2001 Slug (Bouwer test Rice) & 324538.12 HydroGeoLogic,Inc. HydroGeoLogic, (2002) Inc. (2002) F–212 8 6961289.980 972605.03 2001 Slug (Bouwer test Rice) & 2295807.270 10 HydroGeoLogic,Inc. (2002) F–214 324537.96 6961575.610 2001 Slug (Bouwer test Rice) & 972606.73 2296062.430 100 HydroGeoLogic,Inc. HydroGeoLogic, (2002) F–216Inc. (2002) 324540.76 Slug (Bouwer test Rice) & 972603.71 2001 HydroGeoLogic,Inc. (2002) F–217 2001 80 6967838.170 Slug (Bouwer test Rice) & F–218 2290527.370 2001 Slug HydroGeoLogic, (Bouwer test Rice) & Inc. 50 (2002) 6966040.040 324643.27 972707.80 2289864.000 Slug (Bouwer test HydroGeoLogic, Rice) & Inc. (2002) 6965776.180 324625.55 2001 972715.78 2290219.930 HydroGeoLogic,Inc. (2002) 6965959.980 324622.90 972711.64 2290109.050 2001 Slug (Bouwer test Rice) & HydroGeoLogic,Inc. (2002) 6964024.490 324624.73 .05 2291474.210 972712.92 Slug (Bouwer test Rice) & 324605.45 .01 HydroGeoLogic,Inc. (2002) 972657.15 HydroGeoLogic,Inc. 1986 (2002) .06 1 HydroGeoLogic,Inc. (2002) 1986 Cedergen method 1986 Cedergen method .1 HydroGeoLogic,Inc. (2002) Cedergen method 1986 HydroGeoLogic,Inc. (2002) 1986 Cooper type-curve method Cedergen Joint Reserve Base Carswell Field, Fort Worth, Texas—Continued. Worth, Fort Field, Carswell Base Reserve Joint Table 2. Table Introduction 7 Source of test data Air Force Plant 4 and Naval Air Station- Air Naval and 4 Plant Force Air method, or both Test method or analysis Test date Hydraulic conductivity Latitude Longitude 2 Easting 1 Northing Locationsresultspre-2002 andused of estimate aquifertests hydraulic alluvial to slug conductivity and aquifer in underlying Well number F–219F–220F–221HM–10 6964343.310HM–11 2291472.820 6964050.320 324608.60HM–12 972657.14 2290236.600 6963244.600 324605.83HM–25 972711.65 2290575.220 6965810.910 324557.82 2290121.800HM–27 972707.77 6963091.760 324623.26 0.05 2290932.280 972712.79HM–28 6963088.530 324556.27 2290396.720 972703.61 .08HM–30 1986 6963314.260 324556.29 2290575.870 972709.88 .4HM–51 6965727.600 324558.51 Cedergen method .4 1986 2289864.570 972707.76HM–69 6963532.120 324622.46 .4 Cedergen method 2290422.230 972715.81 1986HM–80 6964012.620 324600.68 .01 1986 2289983.860 972709.53HM–88 Cedergen method 6966666.000 324605.47 .07 1986 Cooper type-curve method 2290329.000 972714.61HM–89 1986 6963423.000 324631.70 .5 Cooper type-curve method 2292001.000 972710.26HM–89 1986 6967856.000 324559.44 Cooper type-curve method .1 2290527.000 972651.06RW–8UR 6964479.910 324643.45 Cooper type-curve method .8 1986 2291919.170 972707.80OW–1–1 6964470.440 324609.91 .02 1986 Cooper type-curve method 972651.89 2292084.170 Intellus CorporationOW–1–2 (1986) 6964470.440 324609.80 .7 1986 6964339.000 Intellus Cooper Corporation type-curve method (1986) 972649.96 2292084.170OW–1–3 2291990.600 1986 324609.80 Intellus 100 Corporation (1986) .02 324608.51 Intellus Cooper Corporation type-curve method (1986) 972649.96 6965550.173OW–1–4 972651.07 Intellus Corporation Cooper type-curve 300 (1986) method 2289764.434 1986 Intellus Corporation (1986) 6965548.475 324620.71OW–1–5 1986 Intellus Corporation 100 (1986) 2289789.573 972717.00 Cooper type-curve 100 method 6965546.001 324620.69 1996OW–3–2 Cooper type-curve method 2289833.225 972716.71 Intellus Corporation (1986) 6965577.715 324620.66 100 1996OW–3–6 Aquifer (drawdown) test 2289739.079 972716.20 Intellus Corporation (1986) 6965602.369 324620.98 300 1996OW–3–7 Aquifer (drawdown) test 1996 2289739.743 972717.30 Intellus Corporation (1986) 6966022.931 324621.23 100T4 Aquifer (recovery) test Intellus Corporation (1986) 2289854.960 972717.28 Aquifer (drawdown) test 1994 6966019.660 324625.38 200T6 2289820.920 972715.89 1994 Intellus Corporation (1986) Drawdown (Theis) 6966030.345 324625.35 100T7 Intellus Corporation (1986) 2289827.893 972716.28 1994 Drawdown (Theis) 324625.46HM–89 972716.20 1994 1 Intera(1998) Drawdown (Theis)HM–89 1994 Intera(1998) Drawdown 6965870.000 (Theis)HM–112 .6 2290067.000 Drawdown 6965927.000 324623.85 (Theis)W–149 .2 Intera(1998) Intera (1998) 2290069.000 972713.42 6964470.440 1994 6966050.000 324624.41 2292084.170W–149 1994 2290097.000 972713.39 6964470.440 324609.80 Drawdown (Theis) 324625.62 2292084.170 972649.96 6964218.830WJETA031 1994 40 972713.05 Drawdown 324609.80 (Theis) 2293142.650 972649.96 324607.20 InternationalWJETA033 Technology Corporation (1994) 20 Drawdown (Theis) 6965190.700 972637.59 30 2292456.970 InternationalWJETA036 Technology 6964012.290 Corporation (1994) 20 100 6965190.700 324616.89 2291516.210 2000 972645.51 2292456.970 InternationalWJETA040 Technology 6964003.180 324605.32 Corporation (1994) 324616.89 972656.66 2291520.300 3 2000 972645.51 Slug (Bouwer test Rice) & InternationalWJETA043 Technology 6964011.480 324605.23 Corporation (1994) 1996 2291538.510 972656.62 2000 Slug (Bouwer test Rice) 1996 & InternationalWJETA044 Technology 6964020.130 324605.31 Corporation (1994) 10 Slug (Bouwer test Rice) & .5 972656.40 2291534.390 Slug (Bouwer test Rice) & WJETA047 6964667.720 324605.40 Slug (CPB test Method) 1998 70 .4 972656.45 2292227.720 International Technology Corporation (1994) WJETA050 6964591.320 324611.73 200 Slug (Bouwer test Rice) & International 972648.25 2292172.930 Technology Corporation 1998 (1994) WJETA052 6964393.060 324610.99 1998 40 International 972648.90 2292176.360 Technology Corporation 1998 (1994) Slug (Bouwer test Rice) & InternationalTechnology Corporation (2000) 6964218.300 324609.02 1998 Slug (CPB test Method) 30 972648.89 2293120.620 1998 Slug (CPB test Method) InternationalTechnology Corporation (2000) 6964321.270 324607.20 Slug (CPB test Method) 10 Jacobs Engineering Group, Inc. (1999) 972637.85 2292210.750 Slug (CPB test Method) InternationalTechnology Corporation (2000) 324608.31 1998 30 972648.49 Jacobs Engineering Group, Inc. (1999) 1998 Slug (CPB test Method) Jacobs 30 Engineering Group, Inc. (1999) 1998 Slug (CPB test Method) 40 Jacobs Engineering Group, Inc. (1999) 1998 Slug (CPB test Method) Jacobs Engineering Group, Inc. (1999) 1998 Slug (CPB test Method) Jacobs Engineering Group, Inc. (1999) Jacobs Engineering Group, Inc. (1999) 1998 Slug (Bouwer test Rice) & Jacobs Engineering Group, Inc. (1999) Slug (CPB test Method) Jacobs Engineering Group, Inc. (1999) Jacobs Engineering Group, Inc. (1999) Jacobs Engineering Group, Inc. (1999) Jacobs Engineering Group, Inc. (1999) Jacobs Engineering Group, Inc. (1999) Jacobs Joint Reserve Base Carswell Field, Fort Worth, Texas—Continued. Worth, Fort Field, Carswell Base Reserve Joint Table 2. Table 8 Analyses and Estimates of Hydraulic Conductivity in Alluvial Aquifer Underlying AFP4 and NAS–JRB, Fort Worth, Texas Source of test data Air Force Plant 4 and Naval Air Station- Air Naval and 4 Plant Force Air ate Plane coordinates. In this application, the reference location N65616666.67.coordinates.reference this is application,Plane In the ate Plane coordinates. In this application, the reference is E1968500.00. method, or both Test method or analysis Test date Hydraulic conductivity Latitude Longitude 2 e north-south distance, in feet, of a location from a reference location of known St oflocation known reference a location from a of e north-south in feet, distance, Easting 1 Northing Locationsresultspre-2002 andused of estimate aquifertests hydraulic alluvial to slug conductivity and aquifer in underlying Well number Northing—Northth of State Plane coordinate feet, Plane State ofof coordinate in Easting—North a location distance, east-west of a the State known location from reference 1 2 WJETA058WJETA059WJETA060 6963890.850 2290868.750WJETA063 6963915.190 324604.18 972704.26 2290869.120WJETA064 6963891.670 324604.42 972704.26 2290888.760WJETA065 6963914.990 324604.19 10 972704.03 2290888.600WJETA085 6963902.980 324604.42 972704.03 2290868.450 4WJETA087 6963903.290 324604.30 2290888.750 972704.26 8WL–091JETA 6964032.920 324604.31 1998 30 972704.03 2291528.420WL–091JETA 6964207.710 324605.52 6964267.890 Slug (CPB test Method) 1998 972656.52 2293100.390 2291919.330 5WL–092JETA 324607.09 6964267.890 324607.81 1998 972638.09 Slug (CPB test Method) 972651.91 2291919.330 5WL–092JETA 1998 6963916.770 324607.81 20 Slug (Bouwer test Rice) & 2291884.400 972651.91WL–093JETA 6963916.770 Slug (Bouwer test 324604.34 Rice) & 300 30 1998 2291884.400 972652.36WL–093JETA 6964060.090 324604.34 300 1998 Slug (CPB test Method) 2291864.930 972652.36WL–094JETA 1998 6964060.090 324605.76 600 Slug (Bouwer test Rice) & 972652.57 2291864.930 1998 JacobsWL–094JETA Engineering Group, Inc. (1999) 1998 6964126.840 Slug (CPB test 324605.76 Method) 600 2291827.100 972652.57 1998WL–095JETA Aquifer (drawdown) test 6964126.840 Slug (Bouwer test 324606.42 Rice) & 300 Jacobs Engineering Group, Inc. (1999) Jacobs Engineering Group, Inc. (1999) 972653.01 2291827.100 1998W–149 Aquifer (recovery) test 6964195.430 Jacobs 324606.42 Engineering 300 Group, Inc. (1999) 2291863.320 972653.01 1998F–208 Aquifer (drawdown) test 324607.10 500 972652.58 1998F–212 Aquifer (recovery) test 400 Jacobs Engineering Group, Inc. (1999) Jacobs Engineering Group, Inc. (1999) 1998F–216 Aquifer (drawdown) test 400 6965190.700 2292456.970 1998 JacobsF–217 Engineering Group, Inc. (1999) Aquifer (recovery) test Jacobs Engineering Group, Inc. (1999) 324616.89 Jacobs 6968601.960 Engineering Group, Inc. (1999) 972645.51 1998HM–105 Aquifer (drawdown) test 2290644.230 6967838.170 324650.82 1998HM–12 Aquifer (recovery) test 972706.34 2290527.370 Jacobs Engineering Group, Inc. (1999) Jacobs 6965776.180 324643.27 Engineering Group, Inc. (1999) HM–27 Aquifer (drawdown) test 972707.80 2290219.930 .3 6965959.980 324622.90 6969064.250HM–28 972711.64 2290109.050 Jacobs Engineering Group, Inc. (1999) 2290972.320 Jacobs Engineering 324624.73 Group, Inc. (1999) .7 324655.36W–131U 972712.92 6963088.530 972702.44 1995 2290396.720 .01W–136 Jacobs Engineering Group, Inc. (1999) 6965727.600 324556.29 6 Jacobs Engineering Group, Inc. (1999) Slug (Bouwer test 972709.88 2289864.570 Rice) & 1995W–140 6963532.120 324622.46 7 1995 8 972715.81 2290422.230 6963278.410W–141U Slug (Bouwer test Rice) & Jacobs Engineering Group, Inc. (1999) 324600.68 2290540.830 Jacobs Slug Engineering (Bouwer test Rice) & Group, Inc. (1999) 972709.53 324558.16W–143 1995 972708.17 6965214.160 .1 2290716.200W–144 3 1995 Slug (Bouwer test Rice) & 1995 6965407.490 324617.29 20 6965391.580 972705.89 2291039.700W–147 Slug (Bouwer test Rice) & 30 2290672.520 324619.17 Slug (Bouwer test Rice) 1995 & RUSTGeotech (1995) 324619.05 972702.08W–153 972706.38 6968548.580 Slug (Bouwer test Rice) & 1995 20 2291192.240W–156 RUSTGeotech (1995) 1995 6965577.000 324650.24 RUSTGeotech (1995) 30 Slug (Bouwer test Rice) & 972659.93 2290450.000 1995W–158 6965823.630 324620.91 Slug (Bouwer test Rice) & 972708.97 2290710.240W–159 .2 Slug (Bouwer test Rice) & RUSTGeotech (1995) 6965106.300 324623.32 1995 80 972705.89 2294096.200W–160 RUSTGeotech (1995) 6964824.120 324615.89 300 1995 RUSTGeotech (1995) Slug (Bouwer test Rice) & 972626.32 2292815.020FT08–11A 1995 6963954.830 324613.22 Slug (Bouwer test Rice) & RUSTGeotech (1995) 2291080.820 972641.36LF05–5E 1 Slug (Bouwer test Rice) & 6963922.850 324604.80 1995 10 RUSTGeotech (1995) 972701.77 2291370.780 1995 6962320.500 6963448.680 324604.45 RUSTGeotech (1995) Slug (Bouwer test Rice) & 2295877.800 972658.38 2291368.510 RUSTGeotech (1995) Slug (Bouwer test Rice) & 324548.15 324559.76 .05 6961177.140 1995 972605.78 972658.46 9 2295546.400 1995 RUSTGeotech (1995) 324536.86 50 Slug (Bouwer test Rice) & 1995 972609.80 Slug RUST (Bouwer test Geotech Rice) & (1995) 10 20 RUSTGeotech (1995) Slug (Bouwer test Rice) & 1995 70 1995 RUSTGeotech (1995) Slug (Bouwer test Rice) & RUSTGeotech (1995) 1995 Slug (Bouwer test Rice) & -- Slug (Bouwer test Rice) & RUSTGeotech (1995) -- Slug (Bouwer test Rice) & RUSTGeotech (1995) RUSTGeotech (1995) Slug (Bouwer test Rice) & RUSTGeotech (1995) RUSTGeotech (1995) RUSTGeotech (1995) -- -- Joint Reserve Base Carswell Field, Fort Worth, Texas—Continued. Worth, Fort Field, Carswell Base Reserve Joint Table 2. Table Slug Tests 9 identified as “upper aquifer” wells, some of these wells are by adding (or removing) an object of known volume, such as screened in upper parts of the Goodland-Walnut confining unit. a solid slug, to (or from) a static column of water in a well Hydraulic-conductivity estimates from 18 of the 23 tests were and measuring the resulting changes in water level over time. retained for this report. The changes in water level are recorded until equilibrium is During 1991, Radian Corporation completed 17 slug tests restored—that is, the water level in the well returns to its origi- on AFP4 (Environmental Science and Engineering, Inc., 1994). nal static condition. A principal benefit of slug tests as opposed Hydraulic-conductivity estimates from 11 of the 17 tests are to aquifer tests is that there is no need to dispose of potentially documented in this report. contaminated water. A major limitation of slug tests is that During 1994, International Technology Corporation hydraulic conductivity is estimated for only a few feet from the (1994) conducted eight drawdown tests in the alluvial aquifer. well (Bouwer, 1978, p. 114). The resulting hydraulic-conductivity data were reported as part The areal distribution of hydraulic-conductivity data from of pre-construction testing by International Technology Corpo- previous studies was reviewed, and on the basis of the findings ration for a vacuum-enhanced pumping system at landfill 3. of this review, wells in the alluvial aquifer were selected for the International Technology Corporation (2000) also completed two series of slug tests, October 2002 and August 2003 (pl. 1). three slug tests west of the assembly building as part of a subse- The following three sections describe the conditions and proce- quent remediation investigation. dures for the two series of slug tests. RUST Geotech (1995) completed 25 slug tests in the allu- vial aquifer in the western part of the study area as part of their Theory preliminary assessment and inspection of AFP4 during 1995. Their report indicates that three of the tests were done in wells Data obtained from the October 2002 and August 2003 with screens extending into the weathered top of the Goodland- slug tests were used to estimate hydraulic conductivity from Walnut confining unit and thus are not included with the RUST an analytical relation between the instantaneous displacement Geotech (1995) results in this report (table 2). Hydraulic- of water in a well bore and the resulting rate of head change. conductivity values from 21 of the 25 tests were retained for this These analyses are based on a procedure developed by Bouwer report. and Rice (1976) for fully or partially penetrating wells in uncon- During October 1996, Intera (1998) completed four aqui- fined aquifers. Bouwer and Rice use a modified version of fer tests beneath the east parking lot of AFP4. These tests were the Theim equation (Lohman, 1972) to estimate hydraulic a precursor to Intera’s “partitioning interwell tracer testing” conductivity: (PITT) at AFP4 (Intera, 1998). 2 r 1nR()⁄ r 1 y Jacobs Engineering Group, Inc. (1999), reported the K = ------c e w ---1n----0 , (1) results of 22 slug and nine aquifer tests completed in the east 2L t yt parking lot of AFP4 during 1998. Most of these tests were used where to design a pump-and-treat remediation system, which currently K = hydraulic conductivity [L/T]; (2004) operates in the east parking lot. r = radius of the well casing [L]; During January 1998, CH2M Hill, Inc. (2000), completed c R = effective radial distance over which the head differ- 22 slug tests near the northern lobe of the TCE plume beneath e ence is dissipated [L]; NAS–JRB (fig. 1). These tests (20 of which are listed in table 2) r = radial distance between well center and undisturbed were done to augment information about the alluvial aquifer in w aquifer [L]; this area. L = screened interval [L]; During October–November 1997 Duke Engineering and Services, Inc. (1998), conducted four aquifer tests in wells y0 = difference between static (undisturbed pre-test) and installed in the east parking lot of AFP4. The tests were in wells slug-displaced water levels at time 0 [L]; located where the confining unit beneath the alluvial aquifer is yt = difference between static (undisturbed pre-test) and only a few feet thick. slug-displaced water levels at time t [L]; and HydroGeoLogic, Inc. (2002) did two aquifer tests in the t = time [T]. southern part of NAS–JRB in 1990. In 2000, they did a series of This solution for hydraulic conductivity assumes that (1) the multiple-well aquifer tests in the same general area; and in aquifer is homogeneous and isotropic, (2) water-level change 2001, 16 slug tests. around the well is negligible, and (3) no water flows through any unsaturated material above the water table (Bouwer, 1978, p. 115). Slug Tests Equipment Slug testing (Butler, 1997) is a relatively simple, quick, and inexpensive way to collect data for estimating hydraulic Relative to the amount of equipment required for aquifer conductivity for small areas of an aquifer. A slug test is done testing, little equipment is needed for slug testing. In addition to 10 Analyses and Estimates of Hydraulic Conductivity in Alluvial Aquifer Underlying AFP4 and NAS–JRB, Fort Worth, Texas the required solid object (slug), a pressure transducer and data size. As testing proceeded, however, it became obvious that a logger are useful for measuring and recording the resulting greater choice of slugs was needed to handle the wide variations water-level changes (Butler, 1997, p. 29–44). in well construction (table 4) and the large differences in water The slugs used for this study were hand-built from differ- levels. Therefore, nine slugs were built and used for the August ent diameters and lengths of polyvinyl-chloride (PVC) pipe, 2003 series of tests. which were filled with sand and capped at both ends. Because A 261 QC pressure transducer was used to measure the the casings of wells selected for testing during October 2002 changes in water levels in all wells tested. A Hermit 3000 data had inner diameters of either 2 or 4 inches (table 3), four slugs logger was used to record the measured water-level changes were built initially for this series of tests, two for each casing during October 2002. Although that equipment performed com- petently, a MiniTroll data-logging probe was used in conjunc- tion with an IPAQ pocket PC to measure and record the August Table 3. Diameters of wells and dimensions of slugs used to esti- 2003 water-level data. mate hydraulic conductivity in alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Data Collection Fort Worth, Texas.

Casing Slug Well Date of The specific procedures used in this study were refined diameter number Diameter Length slug test largely through trial-and-error experimentation in tests at the (inches) (inches) (feet) first three wells during October 2002 and at the first well during August 2003. Attempts were made to make both falling-head BGSMW06 4 2.25 3.17 October 2002 (slug inserted into well) and rising-head (slug removed from GMI–22–08M 2 1.25 1.00 August 2003 well) tests; however, the water levels resulting from the falling- HM–100 2 1.25 5.08 August 2003 head experiments either oscillated excessively or were consid- HM–119 4 2.25 3.17 October 2002 ered anomalous or inconsistent. Owing to the possibility of HM–124 4 2.25 3.17 October 2002 interference from the unsaturated zone above the water table, previous investigators recommended making only rising-head HM–125 4 2.25 3.17 October 2002 tests if the water table is below the top of the screen (Dominico HM–126 4 2.25 5.13 October 2002 and Schwartz, 1990; Bouwer, 1989). Because water levels were HM–14 4 2.25 3.17 August 2003 below the top of the screen in 15 of the 16 wells tested during HM–23 4 2.25 3.17 August 2003 October 2002 and in 12 of 14 wells tested during August 2003, LF03–3D 2 1.25 2.58 October 2002 only rising-head data were used to estimate the hydraulic- conductivity values (table 5). MW–12 4 2.25 3.17 October 2002 Although attempts were made to record the rates of water- ST14–03 2 1.25 5.13 October 2002 level change on a linear scale, the linear counters of the data ST14–W23 2 1.25 1.00 August 2003 loggers did not always record at frequent enough intervals to USGS06T 2 1.25 1.58 October 2002 adequately track water levels through the first few seconds of WHGLTA009 2 1.25 2.58 October 2002 response. Gaps in the recorded early-time response were most prevalent for wells penetrating the more permeable parts of the WHGLTA010 2 1.25 2.58 October 2002 alluvial aquifer. Consequently, all water-level responses WHGLTA034 2 1.25 2.58 October 2002 recorded during this study were stored on logarithmic time WHGLTA044 2 1.25 1.58 October 2002 scales. WHGLTA049 2 1.25 1.00 August 2003 Readings that initially were recorded during October 2002 at the rate of six every 5 seconds were decreased logarithmically WITCTA001 2 1.25 2.00 August 2003 to one reading every 10 seconds for later parts of the tests. WITCTA019 2 1.25 2.58 October 2002 During August 2003, readings that initially totaled 10 every WJEGTA514 6 2.25 1.08 August 2003 3 seconds were, likewise, reduced logarithmically over the WJEGTA515 6 2.25 2.00 August 2003 course of each test. WJEGTA516 4 2.25 2.00 August 2003 In addition to the above-mentioned adjustments to ensure the most accurate results possible, all subsequent testing was WJEGTA523 4 2.25 1.08 August 2003 done in the following manner: WJEGTA525 4 2.25 2.00 August 2003 1. An electric line (e-line) was used to measure well WJEGTA527 4 2.25 1.08 August 2003 depths and static water levels for computing saturated WJEGTA527 4 2.25 1.58 October 2002 thicknesses; WJEGTA529 4 2.25 1.08 August 2003 2. When possible, the pressure transducer was placed 1 foot WSAICTA027 2 1.25 5.13 October 2002 or more above the bottoms of wells; Slug Tests 11

Table 4. Location and site-characteristic data for wells used to estimate hydraulic conductivity in alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas.

[Latitude and longitude in degrees/minutes/seconds (DDMMSS.SS); depths in feet below land surface]

Depth to Depth to Depth to Well Depth to Depth of base of Northing1 Easting2 Latitude Longitude top of bottom of number water well alluvial screen screen aquifer BGSMW06 6964981.310 2299910.090 324614.07 972518.24 10.85 7.40 17.40 20.22 20.22 GMI–22–08M 6970323.600 2298971.500 324707.02 972528.59 15.47 10.00 22.50 22.50 22.50 HM–100 6963697.000 2289679.000 324602.38 972718.22 37.05 33.50 48.50 49.00 49.00 HM–119 6968726.000 2294271.800 324651.69 972623.84 15.21 9.00 29.00 32.00 32.00 HM–124 6963957.770 2295223.260 324604.41 972613.26 15.53 9.00 24.00 25.00 23.50 HM–125 6965892.460 2295220.140 324623.56 972613.06 20.43 13.00 33.00 33.00 33.00 HM–126 6963121.000 2294300.200 324556.22 972624.16 16.38 16.00 36.00 37.00 37.00 HM–14 6963092.560 2289243.300 324556.44 972723.39 29.15 28.50 38.30 38.30 42.50 HM–23 6963113.580 2288752.310 324556.70 972729.14 35.14 37.10 46.40 46.40 42.00 LF03–3D 6962056.650 2293269.120 324545.79 972636.37 9.06 7.50 14.40 15.40 15.50 MW–12 6966149.320 2300142.000 324625.60 972515.38 8.82 6.94 26.94 28.00 28.00 ST14–03 6964079.970 2299891.620 324605.15 972518.57 7.41 7.85 17.60 17.90 18.20 ST14–W23 6962949.060 2300410.370 324553.91 972512.63 7.75 5.54 9.54 10.50 10.50 USGS06T 6963763.040 2297542.160 324602.25 972546.12 18.58 12.00 22.00 22.50 21.00 WHGLTA009 6965211.650 2297528.700 324616.59 972546.10 20.87 15.00 25.00 25.00 25.00 WHGLTA010 6965580.030 2296770.930 324620.31 972554.94 24.02 18.00 28.00 28.00 28.50 WHGLTA034 6963889.660 2301060.210 324603.15 972504.90 8.93 5.00 15.00 15.00 15.00 WHGLTA044 6961721.400 2297347.370 324542.07 972548.65 5.60 3.50 8.50 9.00 8.00 WHGLTA049 6962329.240 2299269.360 324547.89 972526.07 7.05 4.50 14.50 14.60 14.80 WITCTA001 6969592.010 2296447.730 324700.04 972558.24 16.53 9.50 21.75 22.00 22.00 WITCTA019 6963107.250 2298838.010 324555.63 972531.02 14.90 9.90 19.65 19.90 20.00 WJEGTA514 6962864.000 2296751.000 324553.44 972555.49 8.39 5.35 9.35 9.85 10.00 WJEGTA515 6962863.000 2296894.000 324553.41 972553.82 8.29 7.50 11.50 12.00 13.00 WJEGTA516 6962969.000 2296860.000 324554.46 972554.20 12.70 11.53 15.53 16.03 16.03 WJEGTA523 6962887.000 2296845.000 324553.65 972554.39 8.59 7.18 9.18 9.74 10.00 WJEGTA525 6962800.000 2296820.000 324552.80 972554.69 10.03 7.59 11.59 12.09 12.09 WJEGTA527 (Aug. 2003) 6962856.000 2296937.000 324553.34 972553.32 10.66 7.28 11.28 11.78 12.00 WJEGTA527 (Oct. 2002) 6962856.000 2296937.000 324553.34 972553.32 8.91 7.28 11.28 11.78 12.00 WJEGTA529 6962759.000 2296997.000 324552.37 972552.62 8.86 9.06 11.06 11.56 12.00 WSAICTA027 6962284.321 2294391.604 324547.94 972623.19 19.59 16.50 31.50 34.00 34.00

1 Northing—North State Plane coordinate of the north-south distance, in feet, of a location from a reference location of known State Plane coordinates. In this application, the reference location is N65616666.67. 2 Easting—North State Plane coordinate of the east-west distance, in feet, of a location from a reference location of known State Plane coordinates. In this application, the reference is E1968500.00.

3. Readings from the pressure transducer were allowed to 5. Once slugs were introduced, readings from the transducer stabilize (usually 10 to 15 minutes) before slugs were were allowed to stabilize before tests were initiated; introduced; 6. The data logger was started a few seconds before slugs 4. When possible, slugs were positioned with their bottoms were removed from the well bores; 1 foot or more above the top of transducer and with their tops 1 foot or more below the static water levels (before 7. The resulting rising-head data were collected until slugs were introduced); readings from the pressure transducers stabilized. 12 Analyses and Estimates of Hydraulic Conductivity in Alluvial Aquifer Underlying AFP4 and NAS–JRB, Fort Worth, Texas

Analyses and Estimates of Hydraulic algorithm (eq. 1) using well and water-level data collected (figs. 3, 4; tables 3, 4). Figure 5 and table 5 summarize the Conductivity results of these analyses. Figure 5 is a frequency distribution of hydraulic-conductivity values obtained during this study. The hydraulic-conductivity estimates provided herein The values range from 0.2 to 200 feet per day, and 83 percent were analyzed with a spreadsheet program (Halford and are within the range from greater than 1 to 100 feet per day. Kuniansky, 2002) that solves the Bouwer and Rice (1976) Although the hydraulic-conductivity values from the study rep- resent only a small sample of all possible values, the results appear consistent with a statistical analysis of possible values Table 5. Summary of hydraulic-conductivity estimates, slug (Halford and Kuniansky, 2002). According to Halford and discrepancies, and 90-percent recovery times for wells in alluvial Kuniansky (2002, p. 9), the likely minimum and likely maxi- aquifer underlying Air Force Plant 4 and Naval Air Station-Joint mum values of hydraulic conductivity are 1 and 100 feet per Reserve Base Carswell Field, Fort Worth, Texas. day, respectively, while the extreme possibilities range from 0.01 to 300 feet per day. Time for Hydraulic Slug In addition to listing the values of hydraulic conductivity, Well 90-percent conductivity discrepancy1 table 5 provides the associated slug-discrepancy values (differ- number recovery (feet per day) (percent) (seconds) ence between theoretical and recorded displacement of water) and 90-percent recovery times (time for well to recover 90 per- BGSMW06 10 7 81 cent of difference between static and slug-displaced water GMI–22–08M .2 49 962 levels). Slug discrepancy is an indicator of slug-test validity HM–100 4 10 35 (Halford and Kuniansky, 2002). The smaller the slug discrep- HM–119 200 48 3 ancy, the more likely the slug-displaced water levels reflect HM–124 2 26 329 properties of the aquifer rather than extraneous well conditions. Although slug-discrepancy values less than about 20 percent HM–125 .8 10 692 are optimum, values of about 50 percent are considered HM–126 60 14 6 acceptable for relatively permeable areas of the aquifer (E.L. HM–14 200 19 3 Kuniansky, U.S. Geological Survey, oral commun., 2003). In HM–23 10 29 80 the two instances of a 51-percent discrepancy (table 5), the LF03–3D 10 10 19 authors decided to retain the associated estimates of hydraulic MW–12 7 40 66 conductivity because no other conductivity data are available ST14–03 5 4 33 for the extreme southeastern part of the study area (pl. 1). The decision to retain these hydraulic-conductivity values (as well ST14–W23 10 51 25 as others from tests with slug discrepancies less than but close USGS06T 50 8 7 to 50 percent) is supported by the fact that these data are to be WHGLTA009 2 16 183 initial values for a ground-water-flow model and thus likely will WHGLTA010 .2 21 2,096 be revised during model calibration. WHGLTA034 20 24 16 Recovery time is inversely related to aquifer hydraulic WHGLTA044 9 40 35 conductivity. The 90-percent recovery times range from 3 seconds to 35 minutes (2,096 seconds). Nineteen, or nearly WHGLTA049 8 51 30 two-thirds, of the tested wells recovered 90 percent of their WITCTA001 50 11 5 slug-induced water-level change in less than 2 minutes. The WITCTA019 60 48 4 3-second recovery times were recorded for wells HM–14 and WJEGTA514 7 35 257 HM–119, which are open to parts of the aquifer composed WJEGTA515 2 41 813 mostly of relatively permeable, well-sorted sand or sandy WJEGTA516 9 27 135 gravel, or both. The longest recovery time of 2,096 seconds WJEGTA523 30 46 34 was recorded in well WHGLTA010 for which a lithologic log indicates a saturated zone composed mostly of fine, silty WJEGTA525 4 6 318 sand. Not surprisingly, the estimate of hydraulic conductivity WJEGTA527 (Aug. 238483from that well (0.2 foot per day) is the smallest reported for the 2003) study. WJEGTA527 (Oct. 27737For wells with static water levels below the top of the well 2002) screen (27 of the 30 wells tested), graphs of slug-displaced WJEGTA529 100 19 11 water levels relative to time (figs. 3, 4) sometimes display two WSAICTA027 4 7 28 straight-line segments of different slopes (Bouwer, 1989). This “double straight-line effect” is especially evident for gravel- 1 Slug discrepancy is difference between theoretical displacement of water and observed displacement of water. packed or highly developed wells, or both, in sediments of Analyses and Estimates of Hydraulic Conductivity 13

1.00 1.00 Well BGSMW06 Well HM-119 0 0 /y /y t 0.10 t 0.10 y y

0.01 0.01 00:00 02:53 05:46 08:38 11:31 00:00 00:17 00:35 00:52 01:09 TIME, IN MINUTE:SECOND TIME, IN MINUTE:SECOND

1.00 1.00 Well HM-124 Well HM-125 0 0 /y t /y

0.10 t 0.10 y y

0.01 0.01 00:00 01:26 02:53 04:19 05:46 00:00 07:12 14:24 21:36 28:48 TIME, IN MINUTE:SECOND TIME, IN MINUTE:SECOND

EXPLANATION Straight-line segment of response curve used

yt/y0 Ratio of differences between static and slug-displaced water levels at time t and time 0, respectively

Figure 3. Slug-induced water-level change (normalized) relative to time from slug-test data collected at Air Force Plant 4 (AFP4) and Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB), Fort Worth, Texas, October 2002. 14 Analyses and Estimates of Hydraulic Conductivity in Alluvial Aquifer Underlying AFP4 and NAS–JRB, Fort Worth, Texas

1.00 1.00 Well HM-126 Well LF03-3D 0 0 /y /y t t 0.10 0.10 y y

0.01 0.01 00:00 00:43 01:26 02:10 00:00 00:43 01:26 02:10 02:53 03:36 TIME, IN MINUTE:SECOND TIME, IN MINUTE:SECOND

1.00 1.00 Well MW-12 Well ST14-03 0 0 /y /y t 0.10 t 0.10 y y

0.01 0.01 00:00 02:53 05:46 08:38 00:00 02:53 05:46 08:38 TIME, IN MINUTE:SECOND TIME, IN MINUTE:SECOND

EXPLANATION Straight-line segment of response curve used

yt/y0 Ratio of differences between static and slug-displaced water levels at time t and time 0, respectively

Figure 3—Continued. Analyses and Estimates of Hydraulic Conductivity 15

1.00 1.00 Well USGS06T Well WHGLTA009 0 0 /y /y t t y 0.10 y 0.10

0.01 0.01 00:00 00:43 01:26 02:10 00:00 02:53 05:46 08:38 11:31 14:24 TIME, IN MINUTE:SECOND TIME, IN MINUTE:SECOND

1.00 1.00 Well WHGLTA010 Well WHGLTA034 0 0 /y /y t t

y 0.10 0.10 y

0.01 0.01 00:00 14:24 28:48 43:12 57:36 00:00 01:26 02:53 04:19 TIME, IN MINUTE:SECOND TIME, IN MINUTE:SECOND

EXPLANATION Straight-line segment of response curve used

yt/y0 Ratio of differences between static and slug-displaced water levels at time t and time 0, respectively

Figure 3—Continued. 16 Analyses and Estimates of Hydraulic Conductivity in Alluvial Aquifer Underlying AFP4 and NAS–JRB, Fort Worth, Texas

1.00 1.00 Well WHGLTA044 Well WITCTA019 0 0 /y /y t t

0.10 y

y 0.10

0.01 0.01 00:00 01:26 02:53 04:19 05:46 07:12 00:00 00:43 01:26 02:10 02:53 TIME, IN MINUTE:SECOND TIME, IN MINUTE:SECOND

1.00 1.00 Well WJEGTA527 Well WSAICTA027 0 0 /y t /y t y 0.10 y 0.10

0.01 0.01 00:00 14:24 28:48 43:12 57:36 00:00 02:53 05:46 08:38 TIME, IN MINUTE:SECOND TIME, IN MINUTE:SECOND

EXPLANATION Straight-line segment of response curve used

yt/y0 Ratio of differences between static and slug-displaced water levels at time t and time 0, respectively

Figure 3—Continued. Analyses and Estimates of Hydraulic Conductivity 17

1.00 1.00 Well GMI-22-08M Well HM-100 0 0 /y t /y t

0.10 y 0.10 y

0.01 0.01 00:00 07:12 14:24 21:36 28:48 00:00 00:43 01:26 02:10 TIME, IN MINUTE:SECOND TIME, IN MINUTE:SECOND

1.00 1.00 Well HM-14 Well HM-23 0 0 /y t /y 0.10 t

y 0.10 y

0.01 0.01 00:00 00:17 00:35 00:52 01:09 00:00 00:43 01:26 02:10 02:53 03:36 TIME, IN MINUTE:SECOND TIME, IN MINUTE:SECOND

EXPLANATION Straight-line segment of response curve used

yt/y0 Ratio of differences between static and slug-displaced water levels at time t and time 0, respectively

Figure 4. Slug-induced water-level change (normalized) relative to time from slug-test data collected at Air Force Plant 4 (AFP4) and Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB), Fort Worth, Texas, August 2003. 18 Analyses and Estimates of Hydraulic Conductivity in Alluvial Aquifer Underlying AFP4 and NAS–JRB, Fort Worth, Texas

1.00 1.00 Well ST14-W23 Well WHGLTA049 0 0 /y /y t t 0.10

y 0.10 y

0.01 0.01 00:00 02:53 05:46 08:38 11:31 14:24 00:00 02:53 05:46 08:38 11:31 14:24 TIME, IN MINUTE:SECOND TIME, IN MINUTE:SECOND

1.00 1.00 Well WITCTA001 Well WJEGTA514 0 0 /y /y t t

y 0.10

y 0.10

0.01 0.01 00:00 00:04 00:09 00:13 00:17 00:22 00:00 07:12 14:24 21:36 28:48 TIME, IN MINUTE:SECOND TIME, IN MINUTE:SECOND

EXPLANATION Straight-line segment of response curve used

yt/y0 Ratio of differences between static and slug-displaced water levels at time t and time 0, respectively

Figure 4—Continued. Analyses and Estimates of Hydraulic Conductivity 19

1.00 1.00 Well WJEGTA515 Well WJEGTA516 0 0 /y t /y t

y 0.10 0.10 y

0.01 0.01 00:00 07:12 14:24 21:36 28:48 00:00 02:53 05:46 08:38 TIME, IN MINUTE:SECOND TIME, IN MINUTE:SECOND

1.00 1.00 Well WJEGTA523 Well WJEGTA525 0 0 /y /y t t y 0.10 y 0.10

0.01 0.01 00:00 01:26 02:53 04:19 00:00 14:24 28:48 43:12 57:36 12:00 TIME, IN MINUTE:SECOND TIME, IN MINUTE:SECOND

EXPLANATION Straight-line segment of response curve used

yt/y0 Ratio of differences between static and slug-displaced water levels at time t and time 0, respectively

Figure 4—Continued. 20 Analyses and Estimates of Hydraulic Conductivity in Alluvial Aquifer Underlying AFP4 and NAS–JRB, Fort Worth, Texas

1.00 1.00 Well WJEGTA527 Well WJEGTA529 0 0 /y /y t t y y 0.10 0.10

0.01 0.01 00:00 07:12 14:24 21:36 00:00 00:09 00:17 00:26 00:35 00:43 TIME, IN MINUTE:SECOND TIME, IN MINUTE:SECOND

EXPLANATION Straight-line segment of response curve used

yt/y0 Ratio of differences between static and slug-displaced water levels at time t and time 0, respectively

Figure 4—Continued.

20

18

16

14

12

10

8

6

4 NUMBER OF OCCURRENCES 2

0 0.2–1 >1–10 >10–50 >50–100 >100–200 HYDRAULIC CONDUCTIVITY, IN FEET PER DAY

Figure 5. Frequency distribution of hydraulic-conductivity values obtained from analyses of slug-test data collected from wells in alluvial aquifer, Air Force Plant 4 (AFP4) and Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB), Fort Worth, Texas. Summary 21 relatively low hydraulic conductivity. According to Bouwer conductivity to use as initial values in a ground-water-flow (1989, p. 306–307), the first (upper) slope is most likely associ- model for the site. ated with drainage from a gravel pack or developed zone During October 2002 and August 2003, after reviewing whereas the second (lower) slope represents flow from undis- aquifer- and slug-test data from previous investigations, the turbed parts of the aquifer. For example, the double-line effect USGS completed slug tests in 30 wells penetrating the alluvial is apparent in the graphs for wells HM–124, HM–125, MW–12 aquifer. This report describes the collection, analyses, and dis- (fig. 3), GMI–22–08M, and HM–23 (fig. 4). Whether a graph tribution of hydraulic-conductivity data obtained from slug test- shows a true double straight line is a matter of judgment. In fact, ing three wells at AFP4 and 27 wells at NAS–JRB and summa- many of the graphs do not show distinct single straight-line rizes previously available hydraulic-conductivity data. The responses, thus considerable judgment commonly is required to testing procedures were refined largely through trial-and-error select the best-fit line. experimentation at the first three wells tested during October Other noteworthy conditions encountered during the 2002 and at the first well tested during August 2003. October 2002 and August 2003 tests that might have some The slug tests were done by placing a slug of known vol- effect on the resulting estimates of hydraulic conductivity ume beneath the water level in selected wells, removing the include (1) readings from the data logger might have been too slug, and measuring the resulting water-level recovery over infrequent to record the maximum water-level displacements in time. The rates of water-level recovery were measured with a wells HM–119, HM–14, and WITCTA019; (2) transducer pressure transducer and recorded with a data logger until the signals were unstable in well USGS06T, owing to nearby air- water levels returned to their original static condition. The slugs craft activity; and (3) slugs were incompletely submerged in were made from different diameters and lengths of polyvinyl- wells USGS06T, WHGLTA044, and WJEGTA527. Although chloride pipe, which were filled with sand and capped at both precautions were taken to minimize and correct for all known ends. Although attempts were made to make both falling-head effects of problems related to the slug-testing procedures, it is (slug inserted into well) and rising-head (slug removed from impossible to know whether, or to what extent, the resulting well) tests, only the rising-head data were used to estimate estimates of hydraulic conductivity are affected. For the three hydraulic conductivity. The resulting water-level responses wells in which the slugs were not completely submerged, the were recorded on logarithmic time scales. variables (eq. 1) were adjusted during analysis to account for Data obtained from the slug tests were used to estimate the reduced length of slug. hydraulic conductivity from an analytical relation between the The slug-test results indicate that the alluvial aquifer instantaneous displacement of water in a well bore and the might be clogging locally (presumably with organic matter) resulting rate of water-level change. The analyses are based the as the result of recent bioremediation on NAS–JRB. Some Bouwer and Rice algorithm, which accounts for fully or par- of the wells that were tested are on the site of a phytoremedia- tially penetrating wells in unconfined aquifers. The resulting tion demonstration project that was initiated in 1996 (Shah hydraulic-conductivity values range from 0.2 to 200 feet per and Braun, 2004). Data from four of seven wells inside the day. Eighty-three percent are within the (previously deter- tree stands or within 125 feet downgradient from the tree mined) statistical likely minimum and maximum values of stands (WJEGTA[514, 515, 516, 523, 525, 527, 529]) indicate 1 and 100 feet per day, respectively. Ninety-percent recovery a decrease in hydraulic conductivity compared to those times ranged from 3 seconds to 35 minutes. Nearly two-thirds from 1996 slug tests (table 2, table 5). The possibility of clog- of the tested wells recovered 90 percent of their slug-induced ging is particularly evident with respect to well WJEGTA527. water-level change in less than 2 minutes. The hydraulic-conductivity estimate for this well (2.0 feet Although precautions were taken to minimize and correct per day)—verified by the tests in both October 2002 and for all known effects of problems related to the slug-testing August 2003—is five times less than that estimated from pre-remediation, 1996 data collected from WJEGTA527. procedures, it is impossible to know whether, or to what extent, the resulting estimates of hydraulic conductivity are affected.

Summary References Disposal of hazardous chemicals, including trichloro- ethene (TCE), at Air Force Plant 4 (AFP4) in Fort Worth, Tex., Bouwer, Herman, 1978, Groundwater hydrology: New York, associated with the manufacture of military aircraft and other McGraw-Hill, 480 p. equipment since 1942 has resulted in TCE entering the ground- Bouwer, Herman, 1989, The Bouwer and Rice slug test—An water-flow system beneath AFP4 and migrating to the subsur- update: Groundwater, v. 27, no. 3, p. 304–309. face beneath adjacent Naval Air Station-Joint Reserve Base Bouwer, Herman, and Rice, R.C., 1976, A slug test for deter- Carswell Field (NAS–JRB). The U.S. Geological Survey, in mining hydraulic conductivity of unconfined aquifers with cooperation with the U.S. Air Force, did a series of slug tests at completely or partially penetrating wells: Water Resources AFP4 and NAS–JRB to obtain estimates of horizontal hydraulic Research, v. 12, no. 3, p. 423–428. 22 Analyses and Estimates of Hydraulic Conductivity in Alluvial Aquifer Underlying AFP4 and NAS–JRB, Fort Worth, Texas

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